13.1.22 DROP PROCEDURE and DROP FUNCTION Syntax

DROP {PROCEDURE | FUNCTION} [IF EXISTS] sp_name

This statement is used to drop a stored procedure or function.
That is, the specified routine is removed from the server. You
must have the ALTER ROUTINE
privilege for the routine. (If the
automatic_sp_privileges system variable is
enabled, that privilege and EXECUTE
are granted automatically to the routine creator when the routine
is created and dropped from the creator when the routine is
dropped. See Section 19.2.2, “Stored Routines and MySQL Privileges”.)

The IF EXISTS clause is a MySQL extension. It
prevents an error from occurring if the procedure or function does
not exist. A warning is produced that can be viewed with
SHOW WARNINGS.